fun fact: besides the stereotypical "guys don't care about subtle shade differences because that's a girl thing", the majority of women actually can see more shades of hues than the majority of men. As with most things that are biological in nature, it's not 100%. There are some ladies that can't, and there are some guys that can see the extra colors. Scientists point to our hunter/gatherer days as the reason for this and that guys are better at noticing movement. (i.e. it really was important to eat only the safe berries)